Ground potential rise monitor

ABSTRACT

A device and method for detecting ground potential rise (GPR) comprising a first electrode, a second electrode, and a voltage attenuator. The first electrode and the second electrode are both electrically connected to the voltage attenuator. A means for determining the presence of a dangerous ground potential is connected to the voltage attenuator. The device and method further comprises a means for enabling one or more alarms upon the detection of the dangerous ground potential. Preferably, a first transmitter/receiver is connected to the means for enabling one or more alarms. Preferably, a second transmitter/receiver, comprising a button, is electromagnetically connected to the first transmitter/receiver. Preferably, the means for determining the presence of a dangerous ground potential comprises a means for determining the true RMS voltage at the output of the voltage attenuator, a transient detector connected to the output of the voltage attenuator, or a combination thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of prior application U.S.non-provisional patent application Ser. No. 12/401,033, filed Mar. 10,2009 now U.S. Pat. No. 8,149,128, hereby fully incorporated byreference. This application is also a continuation-in-part of prior PCTapplication PCT/US10/26189, filed Mar. 4, 2010, hereby fullyincorporated by reference.

GOVERNMENT INTERESTS

The United States Government has rights in this invention pursuant tothe employer-employee relationship between the inventors and the U.S.Department of Energy (DOE).

FIELD OF THE INVENTION

A device and method for detecting ground potential rise, preferably forthe detection and notification of a rise in ground potential.

BACKGROUND OF THE INVENTION

As new demands are placed on the electric power system, moretransmission lines are built and/or upgraded in existing right-of-ways,and fewer maintenance outages are accommodated, maintenance personnelare encountering new challenges in their work. One of these challengespertains to Ground Potential Rise (GPR).

During the repair of a transmission line, personal protective groundcables are installed to safely transfer electric current away fromworkers in the area into the earth through a work site ground system.This electric current may be generated by various means, such as,electromagnetic induction from a nearby current carrying line.Unfortunately, the earth is not an ideal conductor and as more currentpasses into the ground, the ground potential of the earth at and aroundthe work site ground increases. As this ground potential changes,workers may be exposed to dangerous voltages.

Currently the only method of safely minimizing GPR is the use of aplurality of grounding cables carrying current into the earth atmultiple points. Unfortunately, this does not solve the problem of GPR,but only lowers peak voltages at the cost of spreading the voltageacross a larger area. This not only fails to eliminate GPR or notifyusers of a GPR issue, but may spread GPR to an area considered away fromthe worksite.

Therefore, there exists a need to safely detect the presence of GPR.Once GPR is detected, specialized equipment (e.g. highly insulatedboots, gloves, etc. . . . ) may be used by workers to perform their worksafely.

SUMMARY OF THE INVENTION

A device and method for detecting ground potential rise (GPR) comprisinga first electrode, a second electrode, and a voltage attenuator. Thevoltage attenuator comprising a first input, a second input, and anoutput. The first electrode is electrically connected to the first inputof the voltage attenuator. The second electrode is electricallyconnected to the second input of the voltage attenuator. A means fordetermining the presence of a dangerous ground potential is connected tothe voltage attenuator. Preferably, the means for determining thepresence of a dangerous ground potential comprises a means fordetermining the true RMS voltage at the output of the voltageattenuator, a transient detector connected to the output of the voltageattenuator, or a combination thereof. The device and method fordetecting ground potential rise (GPR) also comprises a means forenabling one or more alarms upon the detection of the dangerous groundpotential. The means for determining the presence of a dangerous groundpotential and the means for enabling one or more alarms comprises one ormore computers, microcontrollers, or application specific integratedcircuits (ASIC).

Preferably, a first transmitter/receiver is connected to the means forenabling one or more alarms. A second transmitter/receiver iselectromagnetically connected to the first transmitter/receiver. Abutton connected to the second transmitter/receiver.

Preferably, the means for determining the presence of a dangerous groundpotential comprises a means for determining the true RMS voltage at theoutput of the voltage attenuator. In this embodiment, the means forenabling one or more alarms preferably comprises a means for enablingone or more alarms when the true RMS voltage exceeds a firstpredetermined voltage threshold.

Preferably, the means for determining the presence of a dangerous groundpotential comprises a transient event energy detector connected to theoutput of the voltage attenuator. In this embodiment, preferably, thetransient event energy detector has a means for sampling the voltage atthe output of the voltage attenuator at a low-speed and at a high-speed;the high-speed greater than the low-speed. Preferably, the high-speed isequal to or greater than 1,000 Hz, more preferably equal to or greaterthan 2,000 Hz. Preferably, the low-speed is equal to or less than 10 Hz,more preferably 6 Hz. In this embodiment, preferably, the means forenabling one or more alarms comprises a means for enabling one or morealarms when the transient event energy detected by the transient eventenergy detector exceeds a first predetermined transient event energythreshold. Preferably, the first predetermined transient event energythreshold is in Joules or related to Joules, more preferably greaterthan 13 Joules.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one embodiment of a Ground Potential Rise (GPR) MonitorSystem using a true RMS voltage.

FIG. 2 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor Sensor using a true RMS voltage.

FIG. 3 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor Handheld Unit using a true RMS voltage.

FIG. 4 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor Vehicle Unit using a true RMS voltage.

FIG. 5 depicts a preferred embodiment of a voltage attenuator using atrue RMS voltage.

FIG. 6 depicts a flowchart of a preferred operation of a GroundPotential Rise (GPR) Monitor Sensor using a true RMS voltage.

FIG. 7 depicts a flowchart of the events of a preferred operation of aGround Potential Rise (GPR) Monitor Sensor using a true RMS voltage.

FIG. 8 depicts a flowchart of the events of a preferred operation of aGround Potential Rise (GPR) Monitor Handheld Unit using a true RMSvoltage.

FIG. 9 depicts a flowchart of the events of a preferred operation of aGround Potential Rise (GPR) Monitor Vehicle Unit using a true RMSvoltage.

FIG. 10 depicts one embodiment of a Ground Potential Rise (GPR) MonitorSystem using a transient event energy detector.

FIG. 11 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor using a true RMS voltage and a transient event energy detector.

FIG. 12 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor whereby the first control system provides the true RMS voltageand transient event energy detection.

DETAILED DESCRIPTION OF THE INVENTION

A device and method for detecting ground potential rise (GPR) comprisinga first electrode, a second electrode, and a voltage attenuator. Thevoltage attenuator comprising a first input, a second input, and anoutput. The first electrode is electrically connected to the first inputof the voltage attenuator. The second electrode is electricallyconnected to the second input of the voltage attenuator. A means fordetermining the presence of a dangerous ground potential is connected tothe voltage attenuator. Preferably, the means for determining thepresence of a dangerous ground potential comprises a means fordetermining the true RMS voltage at the output of the voltageattenuator, a transient detector connected to the output of the voltageattenuator, or a combination thereof. The device and method fordetecting ground potential rise (GPR) also comprises a means forenabling one or more alarms upon the detection of the dangerous groundpotential. The means for determining the presence of a dangerous groundpotential and the means for enabling one or more alarms comprises one ormore computers, microcontrollers, or application specific integratedcircuits (ASIC).

Preferably, a first transmitter/receiver is connected to the means forenabling one or more alarms. A second transmitter/receiver iselectromagnetically connected to the first transmitter/receiver. Abutton connected to the second transmitter/receiver.

Preferably, the means for determining the presence of a dangerous groundpotential comprises a means for determining the true RMS voltage at theoutput of the voltage attenuator. In this embodiment, the means forenabling one or more alarms preferably comprises a means for enablingone or more alarms when the true RMS voltage exceeds a firstpredetermined voltage threshold.

Preferably, the means for determining the presence of a dangerous groundpotential comprises a transient event energy detector connected to theoutput of the voltage attenuator. In this embodiment, preferably, thetransient event energy detector has a means for sampling the voltage atthe output of the voltage attenuator at a low-speed and at a high-speed;the high-speed greater than the low-speed. Preferably, the high-speed isequal to or greater than 1,000 Hz, more preferably equal to or greaterthan 2,000 Hz. Preferably, the low-speed is equal to or less than 10 Hz,more preferably 6 Hz. In this embodiment, preferably, the means forenabling one or more alarms comprises a means for enabling one or morealarms when the transient event energy detected by the transient eventenergy detector exceeds a first predetermined transient event energythreshold. Preferably, the first predetermined transient event energythreshold is in Joules or related to Joules, more preferably greaterthan 13 Joules.

In one embodiment, a device and method for detecting ground potentialrise (GPR) comprising attenuating, by an attenuation factor, the voltagebetween a first electrode electrically connected to earth and a secondelectrode electrically connected to earth at a distance from the firstelectrode. Preferably, the true RMS voltage of the attenuated voltage isdetermined producing an attenuated true RMS voltage. The attenuated trueRMS voltage is then multiplied by the attenuation factor producing acalculated true RMS voltage. If the calculated true RMS voltage exceedsa first predetermined voltage threshold, a first alarm at a locallocation is enabled. If user input is received at a remote locationacknowledging the first alarm, a first alarm acknowledgment signal istransmitted. The first alarm acknowledgment signal is then received atwhich time the first alarm is disabled.

One embodiment of a GPR monitor system comprises a first electrode, asecond electrode, a voltage attenuator, a true RMS detector, a firstcontrol system, a first alarm, a first transmitter/receiver, a secondtransmitter/receiver, a second control system and a button. The firstelectrode and the second electrode are positioned in the earth at adistance from each other. The voltage attenuator has a first input, asecond input, a selection port, and an output. The true RMS detector hasan input and an output. The first transmitter/receiver and the firstalarm are positioned at a local location. The secondtransmitter/receiver and the button are located at a remote location.

The first electrode is electrically connected to the first input of thevoltage attenuator. Likewise, the second electrode is electricallyconnected to the second input of the voltage attenuator. The output ofthe voltage attenuator is connected to the input of the true RMS voltagedetector. The first control system is connected to the output of thetrue RMS detector, the first alarm, the selection port of the voltageattenuator, and the first transmitter/receiver. The firsttransmitter/receiver is electromagnetically connected to the secondtransmitter/receiver. Preferably, the second control system is connectedto the second transmitter/receiver and a button.

Preferably, the voltage attenuator attenuates the voltage between thefirst electrode and the second electrode by dividing the voltage betweenthe first electrode and the second electrode by an attenuation factorcreating an attenuated voltage. The attenuation factor used by thevoltage attenuator is preferably controlled by the selection port of thevoltage attenuator. The true RMS voltage detector then produces anattenuated true RMS voltage from the attenuated voltage. Preferably, thefirst control system then calculates the true RMS voltage from theattenuated RMS voltage and the attenuation factor by multiplying theattenuated true RMS voltage by the attenuation factor. If the calculatedtrue RMS voltage is greater than a first predetermined voltagethreshold, the first alarm is enabled.

Preferably, a user can then use the button at the remote location toacknowledge the first alarm, at which time the secondtransmitter/receiver transmits a first alarm acknowledge signal. Thefirst alarm acknowledge signal is then received by the firsttransmitter/receiver and the control system disables the first alarm.

FIG. 1

FIG. 1 depicts one embodiment of a GPR monitor system having a firstelectrode 1, a second electrode 3, a voltage attenuator 5, a true RMSdetector 7, a first control system 9, a first alarm 11, and a firsttransmitter/receiver 13 at a local location 15. The embodiment shown inFIG. 1 also has a second transmitter/receiver 17, a second controlsystem 19, and a button 20 at a remote location 22, preferably in theform of a portable device. It is preferred to include the firsttransmitter/receiver 13 and second transmitter/receiver 17, secondcontrol system 19, and button 20, as the remote location 22 provides asa safe place for workers to acknowledge the alarm. In the alternative,the first transmitter/receiver 13 and second transmitter/receiver 17,second control system 19, and button 20 may be omitted, preferablyrelying on other safety measures (e.g. electrically insulated boots,gloves, etc.).

The voltage attenuator 5 has a first input 23, a second input 25, aselection port 27, and output 29. The first electrode 1 is electricallyconnected to the first input 23 of the voltage attenuator 5 by one ormore wires 31. The second electrode 3 is electrically connected to thesecond input 25 of the voltage attenuator 5 by one or more wires 31.

The true RMS detector 7 has an input 33 and an output 35. The input 33of the true RMS detector 7 is connected to the output 29 of the voltageattenuator 5 by one or more wires 31. The first control system 9 isconnected to the output 35 of the true RMS detector 7, the selectionport 27 of the voltage attenuator 5, the first alarm 11, and the firsttransmitter/receiver 13 by one or more wires 31.

The first transmitter/receiver 13 is electromagnetically connected tothe second transmitter/receiver 17. The second control system 19 isconnected to the second transmitter/receiver 17 and the button 20 by oneor more wires 31.

The First Electrode 1 and the Second Electrode 3

The first electrode 1 is preferably positioned at an area of the locallocation 15 most susceptible to GPR, e.g. grounding lines carryingcurrent away from workers. The first electrode 1 is any electricallyconductive connection to ground susceptible to GPR. In a preferredembodiment, the first electrode 1 is electrically connected to agrounding rod, guy wires, power lines supports, or any other groundingmeans for grounding one or more power sources. In a preferredembodiment, the first electrode 1 is electrically connected to agrounding rod used to ground one or more power sources. In anotherembodiment, the first electrode 1 is an electrically conductiveconnection traveling through various components (e.g. pipes, tubes,various building materials, etc. . . . ) to the ground.

The second electrode 3 is positioned at a distance away from the firstelectrode 1. The second electrode 3 is any electrically conductiveconnection to the ground. Preferably, the second electrode 3 ispositioned away from the first electrode 1 and in an area of the locallocation 15 least susceptible to GPR. In one preferred embodiment, thesecond electrode 3 is a conductive metal positioned in the earth atleast ten feet away from the first electrode 1 or any other groundingmeans. In another embodiment, the second electrode 3 is an electricallyconductive connection traveling through various components (e.g. pipes,tubes, various building materials, etc. . . . ) to the ground.

The Voltage Attenuator 5

The voltage attenuator 5 has a first input 23 a second input 25, aselection port 27, and output 29. The first input 23 is electricallyconnected to the first electrode 1 by one or more wires 31. The secondinput 25 is electrically connected to the second electrode 3 by one ormore wires 31. The selection port 27 is connected to the first controlsystem 9 by one or more wires 31. The output 29 of the voltageattenuator 5 is connected to the input 33 of the true RMS detector 7.

The voltage attenuator 5 attenuates the voltage between the first input23 (electrically connected to first electrode 1) and the second input 25(electrically connected to the second electrode 3) and produces anattenuated voltage at its output 29. The attenuated voltage can then beused by low voltage (5 volts and under) digital logic electronics suchas computers, microcontrollers, application specific integrated circuits(ASIC) etc. In one embodiment, the voltage attenuator 5 produces a firstand second output, whereby the voltage between the first and secondoutput is the attenuated voltage. In an alternate embodiment, thevoltage attenuator 5 produces a single output, whereby the voltagebetween the single output and a common ground is the attenuated voltage.

The voltage attenuator 5 produces an attenuated voltage corresponding tothe voltage at the first electrode 1 and the second electrode 3 dividedby an attenuation factor. As the true RMS detector 7 will have thehighest resolution with the least amount of attenuation by the voltageattenuator 5, but also have a maximum operating input voltage, theoutput 29 of the voltage attenuator 5 preferably produces the highestoperating voltage (having the least attenuation) that can be used by thetrue RMS detector 7, especially without damaging the true RMS detector7.

Preferably, the selection port 27 is an input port whereby the voltageattenuator 5 attenuates the voltage between the first electrode 1 andthe second electrode 3 at the direction of the first control system 9through the selection port 27. In the alternative, the selection port 27may be an output port whereby the voltage attenuator 5, or alternately athird control system, produces the attenuation factor, which can be usedby the first control system 9 to determine the calculated true RMSvoltage.

Preferably, the voltage attenuator 5 uses a voltage divider toselectively attenuate the voltage potential between its first input 23(electrically connected to first electrode 1) and its second input 25(electrically connected to the second electrode 3). In the alternative,the voltage attenuator 5 is an operational amplifier, transistor basedcircuit (e.g. transistor selected voltage dividers), or any other meansto attenuate a voltage. In a preferred embodiment, the voltageattenuator 5 is the voltage attenuator 5 depicted in FIG. 5.

Preferably, the voltage attenuator 5 produces between the maximumvoltage and the minimum voltage that can be detected by the true RMSdetector 7. In a preferred embodiment, the voltage attenuator 5, thetrue RMS detector 7 or a combination thereof has a voltage limitingmeans whereby the output 29 of the voltage attenuator 5 has an outputvoltage between the maximum voltage and the minimum voltage of the trueRMS detector 7.

In one embodiment, a first diode and a second diode are used to limitthe voltages of the output 29 of the voltage attenuator 5 between themaximum voltage and the minimum voltage of the true RMS detector 7. Inthis embodiment, the first diode is connected in reverse polarity to theoutput 29 of the voltage attenuator 5 and a voltage source producing themaximum voltage of the true RMS detector 7. Likewise, the second diodeis connected in reverse polarity to the output 29 of the voltageattenuator 5 and a voltage source producing the minimum voltage of thetrue RMS detector 7. Therefore preventing the output 29 of the voltageattenuator 5 from exceeding the maximum voltage and the minimum voltageof the true RMS detector 7.

Preferably the output 29 of the voltage attenuator 5 is an analogoutput. In the alternative, the voltage attenuator 5 produces a digitalsignal to the true RMS detector 7 via a plurality of parallelconnections, a serial data bus, or other digital connection means.

The True RMS Detector 7

The true RMS detector 7 has input 33 and an output 35. The input 33 ofthe true RMS detector 7 is connected to the output 29 of the voltageattenuator 5, preferably by one or more wires 31. The true RMS detector7 determines the true RMS voltage of its input 33. The true RMS detector7 produces an attenuated true RMS voltage, the calculated true RMSvoltage between the first electrode 1 and the second electrode 3attenuated by the attenuation factor of the voltage attenuator 5. Thetrue RMS voltage is the square-root of the average of the square of thevoltage of the input 33. In one embodiment, the voltage of the input 33is squared at a predetermined time interval, averaged for thepredetermined time interval, and square rooted.

The true RMS voltage is preferably calculated without the use ofapproximations, as the GPR may be generated from various sources havingvarious waveforms from one or more combined DC or AC signals havingvarious waveforms. Furthermore, unknown ground conditions at the firstelectrode 1 and the second electrode 3 or other circuitry in the systemmay also act as a filter filtering some frequencies or DC voltages whileallowing others to pass.

In the alternative, the voltage of the input 33 is digitally capturedand stored (e.g. by the first control system 9 or buffer) and after aselect time interval the true RMS is calculated by the square-root ofthe average of the square of the voltage between the stored voltages.Other means of determining the true RMS voltage may be used. In apreferred embodiment, the true RMS voltage is determined by a computer,microcontroller, or an application specific integrated circuit (ASIC).More preferably, the true RMS voltage is determined by an ASIC such asthe AD736 True RMS-to-DC converter.

In the embodiment shown in FIG. 1, the true RMS detector 7 determinesthe true RMS voltage of the attenuated voltage produced at the output 29of the voltage attenuator 5. Preferably, the input 33 of the true RMSdetector is a first input having a corresponding second input, wherebythe voltage between the first input and the second input is theattenuated true RMS voltage. In an alternate embodiment, the input 33 isa single input, whereby the voltage between the single input and acommon ground is the attenuated true RMS voltage.

The attenuated true RMS voltage is then produced at the output 35 of thetrue RMS detector 7. Preferably, the output 35 of the true RMS detector7 is a single output and the true RMS detector 7 shares a common groundwith the first control system 9. In the alternative, the output 35 ofthe true RMS detector 7 may be a first output having a correspondingsecond output, whereby both the first output and the second output areconnected to the first control system 9 and the voltage between thefirst output and the second output is the true RMS voltage.

Preferably the output 35 of the true RMS detector 7 is an analog output,and the first control system 9 has an analog-to-digital converter forreading the voltage outputted by the true RMS detector 7. Forsimplicity, the output 35 of the true RMS detector 7 is treated asproducing an attenuated true RMS voltage. However, the true RMS detector7 will preferably produce a signal symbolic of the attenuated true RMSvoltage. For example, the preferred AD736 True RMS-to-DC converterproduces an analog dc voltage which can be multiplied by a knownmultiplication factor (preferably by the first control system 9) todetermine the attenuated true RMS voltage.

In the alternative, the true RMS detector 7 produces a digital signal tothe first control system 9 via a plurality of parallel connections, aserial data bus, or other digital connection means. Preferably, in thisembodiment the digital signal corresponds to the actual attenuated trueRMS voltage. However, in other embodiments, the digital signal may needto be multiplied by some factor or other calculations may be necessaryfor the actual attenuated true RMS voltage to be calculated (preferablyby the first control system 9).

The First Alarm 11

The first alarm 11 is enabled at the local location 15 notifying theworkers at the local location 15 of potentially unsafe GPR. The firstalarm 11 is preferably connected to the first control system 9 via oneor more wires 31. The first alarm 11 is enabled when the calculated trueRMS voltage is greater than a first predetermined voltage threshold.Preferably, the first alarm 11 is a device capable of creating anaudible signal, visible signal, vibration or a combination thereof. In apreferred embodiment, the first alarm 11 is a horn.

The First Control System 9

The first control system 9 is electrically connected to the selectionport 27 of the voltage attenuator 5, the output 35 of the true RMSdetector 7, the first alarm 11, and the first transmitter/receiver 13,preferably by one or more wires 31. Any means of connecting the firstcontrol system 9 to the various components may be used (e.g. electrical,optical, electromagnetic, etc. . . . ). The first control system 9preferably calculates the true RMS voltage between the first electrode 1and the second electrode 3 by multiplying the output 35 of the true RMSdetector 7 by the attenuation factor used by the voltage attenuator 5.The first control system 9 also performs any conversions necessary toenable the first alarm 11 if the calculated true RMS voltage reading isgreater than the first predetermined voltage threshold.

The first control system 9 preferably controls the voltage attenuator 5to properly attenuate the voltage of the first electrode 1 and thesecond electrode 3. In one alternate embodiment, the first controlsystem 9 receives the attenuation factor from the selection port 27 ofthe voltage attenuator 5. In yet another alternate embodiment, the firstcontrol system 9 receives the attenuation factor from another source,such as a third control system controlling or receiving the attenuationfactor from the voltage attenuator 5.

The control system 9 has the necessary digital-to-analog,analog-to-digital, power relays, electrical switches, etc. . . .necessary to receive, read, control power, or various combinationsthereof the various components connected to the control system 9. Forexample, if the output 35 of the true RMS detector 7 is analog, thefirst control system 9 preferably has an analog-to-digital converterused to convert the voltage produced at the output 35 of the true RMSdetector 7 (attenuated true RMS voltage) to a digital value used by thecontrol system 9. Likewise, the first control system 9 preferably has adigital connection (e.g. data bus, serial connection, parallelconnection) for sending the calculated true RMS voltage to the firsttransmitter/receiver 13. In one alternate embodiment, the first controlsystem 9 has a digital-to-analog converter for sending a calculated trueRMS voltage to the first transmitter/receiver 13. Similarly, the controlsystem 9 preferably uses an electrical switch (relay, transistor, etc. .. . ) to power, therefore enabling, the first alarm 11 or disable thefirst alarm 11.

Various aspects of the first control system 9 may be implemented usingvarious computers, microcontrollers, application specific integratedcircuits (ASICs) or others means. In a preferred embodiment, the firstcontrol system 9 is an Atmel ATMEGA32.

Any number of the voltage attenuator 5, the true RMS detector 7, thefirst control system 9 and the first transmitter/receiver 13 may becombined. For example, in one embodiment, the first control system 9 isa microcontroller capable of determining the attenuated true RMS voltagedirectly from the voltage attenuator, thus serving as both the true RMSdetector 7 as well as the first control system 9. Likewise, in anotherembodiment, the first control system 9 has a means fortransmitting/receiving thus serving as both the firsttransmitter/receiver 13 as well as the first control system 9.

In one embodiment, the first control system 9 has a means for loggingdata comprising RMS voltage readings, preferably with time and datestamps. Preferably, the time and date stamps are generated using a realtime clock (RTC) powered by an independent user replaceable batterybackup, whereby the user may remove or completely discharge a mainbattery without affecting the clock. Preferably, the logged data isstored on a removable media, for example but not limited to: SD card,memory stick, or other magnetic media storage or flash memory baseddevice. Additionally, preferably, the logging data further comprisestransient event energies. In yet another embodiment, the logging datafurther comprises the status of various alarms in the system (e.g. firstalarm 11). Preferably, the logged data is stored in an industry standardformat, for example ASCII. Preferably, the logged data is stored in afile on a predetermined filesystem (e.g. FAT, NTFS, EXT3, EXT4, ZFS,etc) and a more preferably, a new file is created each time the deviceis powered-on. Preferably, if the logged data has filled or will fillthe media storage, files are deleted with the oldest data first.Preferably, if a storage media is not present, the control system 9sends a signal to display a warning to the user, for example an iconindicative that logging has been disabled.

First Transmitter/Receiver 13

The first transmitter/receiver 13 is connected to the first controlsystem 9 and electromagnetically connected to the secondtransmitter/receiver 17. When the first predetermined voltage thresholdis exceeded by the calculated true RMS voltage, the first alarm 11 isenabled by the first control system 9 until a first alarm acknowledgmentsignal is transmitted by the second transmitter/receiver 17 and receivedby the first transmitter/receiver 13.

Preferably, the signal corresponding to the calculated true RMS voltageis transmitted by the first transmitter/receiver 13 and received by thesecond transmitter and receiver 17, more preferably using a protocolsuch as defined in IEEE 802.15.4. In a preferred embodiment, the firsttransmitter/receiver 13 and the second transmitter/receiver 17 are bothan Xbee® transmitter. Preferably, the true RMS voltage is then displayedto a user at the remote location 22.

The Local Location 15

The local location 15 is preferably a worksite. More preferably, thelocal location 15 is a worksite where significant amounts of electricalcurrent are transferred into the earth. The first alarm 11 is enabled atthe local location 15 preferably to notify the workers at the locallocation 15 of potentially unsafe GPR at the local location 15.Preferably, the voltage attenuator 5, true RMS detector 7, first controlsystem 9, first alarm 11, and first transmitter/receiver 13 are allencased within a portable casing.

The Second Transmitter/Receiver 17

The second transmitter/receiver 17 is connected to the second controlsystem 19 and electromagnetically connected to the firsttransmitter/receiver 13. In a preferred embodiment, the secondtransmitter/receiver 17 is an Xbee® receiver. When the calculated trueRMS voltage exceeds the first predetermined voltage threshold, the firstalarm 11 is enabled until a first alarm acknowledgment signal istransmitted by the second transmitter/receiver 17 and received by thefirst transmitter/receiver 13.

In a preferred embodiment, the second transmitter/receiver 17 is anexisting handheld device or an attachment for an existing device.Preferably, the existing device is a smartphone, table, notebook,netbook, or other portable device. In one embodiment, the secondtransmitter/receiver 17 is provided by an existing device or anattachment for an existing device. Preferably, the existing device is adevice using iPhone OS or iOS (e.g. iPad, iPod, iPhone) as created byApple Inc., a device using the Android operating system as created byGoogle (e.g. Google Nexus One, Nexus S, HTC G2, etc.), a device usingthe Windows Mobile or Windows Phone 7 operating system as created byMicrosoft (e.g. HD2, H7).

The Button 20

The button 20 is any means for the user to acknowledge the first alarm11. In one embodiment, this button 20 is a simple push button used totrigger the second control system 19, the second transmitter/receiver17, or a combination thereof to construct and transmit a first alarmacknowledgement signal which is received and understood by the firstcontrol system 9, the first transmitter/receiver 13, or a combinationthereof. In an alternate embodiment, the button 20 is a plurality ofkeys, for example forming a keyboard or other user interface. In yetanother alternate embodiment, the button 20 is a touch sensitive portionor layer of a screen, thereby allowing the user to simply touch thescreen to acknowledge the first alarm 11.

The Second Control System 19

The second control system 19 is connected to the secondtransmitter/receiver 17, and the button 20, preferably by the one ormore wires 31. The second control system 19 with the secondtransmitter/receiver 17 constructs and transmits an acknowledgmentsignal to the first transmitter/receiver 13 to acknowledge an alarmsounded by the first control system 9.

Various aspects of the second control system 19 may be implemented usingvarious computers, microcontrollers, application specific integratedcircuits (ASICs) or others means. In a preferred embodiment, the firstcontrol system 9 is an Atmel ATMEGA32.

In a preferred embodiment, the second control system 9 is provided by anexisting device or an attachment for an existing device. Preferably, theexisting device is a device using iPhone OS or iOS (e.g. iPad, iPod,iPhone) as created by Apple Inc., a device using the Android operatingsystem as created by Google (e.g. Google Nexus One, Nexus S, HTC G2,etc.), a device using the Windows Mobile or Windows Phone 7 operatingsystem as created by Microsoft (e.g. HD2, H7).

Preferably, the first predetermined voltage threshold, the threshold atwhich the first alarm 11 is enabled, is programmable at the remotelocation 22. In one embodiment, the second control system 19 has aplurality of buttons, switches, or other control means to allow the userto select or enter-in the first predetermined true RMS voltage.

The second control system 19 and the second transmitter/receiver 17 maybe combined. For example, in one embodiment, the second control system19 has a means for transmitting/receiving thus serving as both thesecond transmitter/receiver 17 as well as the second control system 19.

The Remote Location 22

The remote location 22 is preferably at a safe distance away from thelocal location 15. More preferably, the remote location 22 is at leastten feet away from the local location 15. Preferably, when the firstalarm 11 is enabled, it produces an alarm significant enough to notifythe workers at the remote location 22 of potentially unsafe GPR at thelocal location 15. The second transmitter/receiver 17, second controlsystem 19, and second alarm 21 are all located at the remote location22, preferably in a compact case.

The One or More Wires 31

The one or more wires 31 are any means to electrically connect thevarious components together. Preferably, the wires are one or moreelectrical conductors. In the alternative any means of connecting thevarious components may be used (e.g. electrical, optical,electromagnetic, etc. . . . ).

FIG. 2

FIG. 2 depicts a preferred embodiment of a GPR monitor sensor having afirst electrode 1, a second electrode 3, a voltage attenuator 5, a trueRMS detector 7, a first control system 9, a first alarm 11, a secondalarm 12, a first display 37, first push buttons 10, and a firsttransmitter/receiver 13 at a local location.

The voltage attenuator 5 has a first input 23, a second input 25, aselection port 27, and output 29. The first electrode 1 is electricallyconnected to the first input 23 of the voltage attenuator 5 by one ormore wires 31. The second electrode 3 is electrically connected to thesecond input 25 of the voltage attenuator 5 by one or more wires 31. Thetrue RMS detector 7 has input 33 and an output 35. The output 29 of thevoltage attenuator 5 is connected to the input 33 of the true RMSdetector 7 by one or more wires 31. The first control system 9 isconnected to the output 35 of the true RMS detector 7, the selectionport 27 of the voltage attenuator 5, the first alarm 11, the secondalarm 12, the first display 37, the first push buttons 10, and the firsttransmitter/receiver 13 by one or more wires 31.

The first control system 9 continuously calculates the true RMS voltagebetween the first electrode 1 and the second electrode 3 (by multiplyingthe attenuated true RMS voltage from the true RMS detector 7 by theattenuation factor of the voltage attenuator 5). If the calculated trueRMS voltage exceeds a first predetermined voltage threshold, the firstalarm 11 is enabled, preferably producing a visual alarm until anacknowledgment is received. Likewise, if the calculated true RMS voltageexceeds a second predetermined voltage threshold, the second alarm 12 isenabled, preferably producing an audible alarm until an acknowledgmentis received. Preferably, both the first alarm 11 and the second alarm 12are each capable of being acknowledged by the first push buttons 10, asignal from a remote handheld unit (e.g. the embodiment shown in FIG.3), a signal from a remote vehicle unit (e.g. the embodiment shown inFIG. 4), or a combination thereof.

In one embodiment, the first control system 9 continuously stores a logof calculated true RMS voltages for retrieval at a later time. In oneembodiment, the first control system 9 stores a database of calculatedtrue RMS voltages on an external flash media (e.g. SD card).

The First Display 37

The first display 37 displays at the local location the calculated trueRMS voltage between the first electrode 1 and the second electrode 3.Preferably, the first display 37 is a cathode-ray-tube (CRT), led array,etc. . . . , more preferably a liquid crystal display (LCD).

The First Alarm 11

In the embodiment shown in FIG. 2, the first alarm 11 preferablyproduces a visual signal via a strobe light, LED, light bulb, etc. . . .. Preferably, the first alarm 11 is a strobe light or other devicecapable of producing a high-intensity light.

The Second Alarm 12

In the embodiment shown in FIG. 2, the second alarm 12 preferablyproduces an audible signal via a horn, speaker, bell, etc. . . . .Preferably, the second alarm 12 is a horn or bell capable of producing aloud sound.

FIG. 3

FIG. 3 depicts a preferred embodiment of a Ground Potential Rise (GPR)monitor handheld unit. The embodiment shown in FIG. 3 has a secondtransmitter/receiver 17, a second control system 19, a second display39, a first alarm 49, a second alarm 51, a third alarm 53, and secondpush buttons 52. The second transmitter/receiver 17 iselectromagnetically connected to the first transmitter/receiver 13 ofFIG. 2. The second control system 19 is connected to the secondtransmitter/receiver 17, the second display 39, the first alarm 49, thesecond alarm 51, the third alarm 53, and the second push buttons 52,preferably by one or more wires 31.

The Second Display 39

The second display 39 displays the calculated true RMS voltage of thefirst electrode 1 and the second electrode 3 shown in FIG. 2.Preferably, the second display 39 is a cathode-ray-tube (CRT), ledarray, etc. . . . , more preferably a liquid crystal display (LCD).

The First Alarm 49

In the embodiment shown in FIG. 3, the first alarm 49 preferablyproduces a visual signal via a strobe light, LED, light bulb, etc. . . .. Preferably, the first alarm 49 is a strobe light or other devicecapable of producing a high-intensity light. In this embodiment, the GPRsensor of FIG. 2 will produce a first alarm enable signal at which timethe first alarm 49 shown in FIG. 3 is enabled until the first alarmdisable signal is transmitted from the GPR sensor of FIG. 2 and receivedby the GPR handheld unit of FIG. 3.

The Second Alarm 51

In the embodiment shown in FIG. 3, the second alarm 51 preferablyproduces an audible signal via a horn, speaker, bell, etc. . . . .Preferably, the second alarm 12 is a horn or bell capable of producing aloud sound. In this embodiment, the GPR sensor of FIG. 2 will produce asecond alarm enable signal at which time the second alarm 51 shown inFIG. 3 is enabled until the second alarm disable signal is transmittedfrom the GPR sensor of FIG. 2 and received by the GPR handheld unit ofFIG. 3.

The Third Alarm 53

In the embodiment shown in FIG. 3, the third alarm 53 preferablyproduces a mechanical signal, preferably a vibration by the use of amotor rotating a weight, an electromechanical hammer, or any other meansof generating a vibration. Preferably, the third alarm 53 is a motorrotating an unbalanced weight.

The second control system 19 enables the third alarm 53 whenever thefirst alarm 49, the second alarm 51 or a combination there of isenabled. Once both the first alarm 49 and the second alarm 51 aredisabled, second control system 19 disables the third alarm 53.

FIG. 4

FIG. 4 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor Vehicle Unit. The embodiment shown in FIG. 4 has a thirdtransmitter/receiver 55, a third control system 57, a third display 59,a first alarm 63, a second alarm 65, and third push buttons 61. Thethird transmitter/receiver 55 is electromagnetically connected to thefirst transmitter/receiver 13 of FIG. 2. The third control system 57 isconnected to the third transmitter/receiver 55, the third display 59,the first alarm 63, the second alarm 65, and third push buttons 61,preferably by one or more wires 31.

The Third Display 59

The third display 59 displays the calculated true RMS voltage of thefirst electrode 1 and the second electrode 3 shown in FIG. 2.Preferably, the third display 59 is a cathode-ray-tube (CRT), led array,etc. . . . , more preferably a liquid crystal display (LCD).

The First Alarm 63

In the embodiment shown in FIG. 4, the first alarm 63 preferablyproduces a visual signal via a strobe light, LED, light bulb, etc. . . .. Preferably, the first alarm 63 is a strobe light or other devicecapable of producing a high-intensity light. Preferably, the first alarm63 in this embodiment is powered by a vehicle battery. In oneembodiment, the first alarm 63 is a strobe light on a vehicle or avehicles fog lights or headlights. In this embodiment, the GPR sensor ofFIG. 2 will produce a first alarm enable signal at which time the firstalarm 63 shown in FIG. 4 is enabled until the first alarm disable signalis transmitted from the GPR sensor of FIG. 2 and received by the GPRvehicle unit of FIG. 4.

The Second Alarm 65

In the embodiment shown in FIG. 4, the second alarm 65 preferablyproduces an audible signal via a horn, speaker, bell, etc. . . . .Preferably, the second alarm 65 is a horn or bell capable of producing aloud sound. Preferably, the second alarm 65 in this embodiment ispowered by a vehicle battery. In one embodiment, the second alarm 65 isa vehicle horn. In this embodiment, the GPR sensor of FIG. 2 willproduce a second alarm enable signal at which time the second alarm 65shown in FIG. 4 is enabled until the second alarm disable signal istransmitted from the GPR sensor of FIG. 2 and received by the GPRvehicle unit of FIG. 4.

FIG. 5

FIG. 5 depicts one embodiment of the voltage attenuator 5 in FIG. 1 andFIG. 2. In this embodiment, the voltage attenuator 5 comprises a firstresistor 41, a plurality of selectable resistors 43, and an analogmultiplexer 45.

The first resistor 41 has a first end and a second end. Likewise, eachselectable resistor from the plurality of selectable resistors 43 has afirst end and a second end. The analog multiplexer 45 has a plurality ofinputs, an output and a selection port.

The first end of the first resistor 41 is the first input 23 of thevoltage attenuator 5 (electrically connected to the first electrode 1 inFIG. 1 and FIG. 2). The second end of the first resistor 41 iselectrically connected to the first end of each selectable resistor fromthe plurality of selectable resistors 43 and the output 29 of thevoltage attenuator 5 (electrically connected to the input 33 of the trueRMS detector 7 in FIG. 1 and FIG. 2). The second end of each selectableresistor from the plurality of selectable resistors 43 is electricallyconnected to a corresponding input from the plurality of inputs of theanalog multiplexer 45. The output of the analog multiplexer 45 is thesecond input 25 of the voltage attenuator 5 (electrically connected tothe second electrode 3 in FIG. 1 and FIG. 2). The selection port 27 ofthe voltage attenuator 5 is the selection port of the analog multiplexer5 (electrically connected to the first control system 9 in FIG. 1 andFIG. 2).

In a preferred embodiment, the second electrode 3, connected to theoutput of the analog multiplexer 45, is also connected to the true RMSdetector 7 (not shown for simplicity) in FIG. 1 and FIG. 2. Thisembodiment will be desirable when the second electrode 3 is not used asa common ground within the GPR Monitor Sensor. In an alternateembodiment, the second electrode 3 is a common relative ground connectedto both the voltage attenuator 45 (through the second input 25) and thetrue RMS detector 7.

The First Resistor 41 and the Plurality of Selectable Resistors 43

The first resistor 41 and the plurality of selectable resistors 43 areresistors capable of handling the voltage and current it will likely besubjected to in the field. In a preferred embodiment, the first resistor41 is a 10M ohm resistor and the plurality of selectable resistors 43are 1K, 10.2K, 102K and 1.10M ohm resistors.

The Analog Multiplexer 45

The analog multiplexer 45 is an analog multiplexer capable ofelectrically connecting the second end of a selectable resistor from theplurality of selectable resistors 43 to the output of the analogmultiplexer 45 (the second input 25 of the voltage attenuator 5 in FIG.1 and FIG. 2). The analog multiplexer 45 also is capable of handling thevoltage and current it will likely be subjected to in the field. In apreferred embodiment the multiplexer is a 74HC4052B.

FIG. 6

FIG. 6 depicts a flowchart of a preferred operation of a GPR monitorsensor. As shown in FIG. 6, the GPR monitor attenuates the voltagebetween the first electrode and the second electrode. The attenuatedvoltage is then detected and the true RMS of the attenuated voltage iscalculated to determine the attenuated true RMS voltage. Finally, theattenuated true RMS voltage is multiplied by the attenuation factor,which produces the calculated true RMS voltage. Preferably, thecalculated true RMS voltage is then displayed at a local location aswell as transmitted to remote units for display (e.g. the handheld unitin FIG. 3 or the vehicle unit in FIG. 4).

If the calculated true RMS voltage exceeds the first predeterminedvoltage threshold, the first alarm of the GPR monitor is enabled andpreferably a first alarm signal is transmitted to the remote units.Therefore, the first alarm of the GPR monitor sensor and preferably anyremote units will be enabled until acknowledged by a user.

Likewise, if the calculated true RMS voltage exceeds the secondpredetermined voltage threshold, the second alarm of the GPR monitor isenabled and preferably a second alarm signal is transmitted to theremote units. Therefore, the second alarm of the GPR monitor sensor andpreferably any remote units will be enabled until acknowledged by auser.

FIG. 7

FIG. 7 depicts a flowchart of the events of a preferred operation of aGPR monitor sensor. As shown in FIG. 7, if the GPR monitor sensor eitherreceives a first alarm acknowledge signal from a remote unit or a pushbutton is pressed acknowledging the first alarm, the first alarm of theGPR monitor sensor is disabled and a first alarm disable signal istransmitted. Once disabled the first alarm is disabled, preferably untilthe sensor is reset by the user, disconnected from the first electrodeand second electrode, a time period has elapsed, or the calculated trueRMS voltage substantially changes.

Likewise, if the GPR monitor sensor either receives a second alarmacknowledge signal from a remote unit or a push button is pressedacknowledging the second alarm, the second alarm of the GPR monitorsensor is disabled and a second alarm disable signal is transmitted.Once disabled the second alarm is disabled, preferably until the sensoris reset by the user, disconnected from the second electrode and secondelectrode, a time period has elapsed, or the calculated true RMS voltagesubstantially changes.

The first alarm disable signal and the second alarm disable signal areany means of signaling to the remote units that the alarms should bedisabled. In a preferred embodiment, the respective disabled signals arean electromagnetic signal transmitted causing the remote units todisabled the corresponding alarms. In the alternative, the respectivealarm signals are continuously transmitted and the disable signal issimply a discontinuance of these enable signals. Preferably in thisembodiment, the enable signal enables the corresponding alarm for apredetermined time period, preferably under a second) to account for anycommunication errors and communication bandwidth.

FIG. 8

FIG. 8 depicts a flowchart of the events of a preferred operation of aGPR monitor handheld unit (e.g. the embodiment show in FIG. 3). As shownin FIG. 8, the GPR monitor handheld unit preferably receives thecalculated true RMS voltage from the GPR monitor sensor (e.g. theembodiment show in FIG. 2) and displays the received calculated true RMSvoltage at the GPR monitor handheld unit.

If the GPR monitor handheld receives a first alarm enable signal, thefirst alarm of the GPR monitor handheld unit is enabled, as well as thethird alarm. Thereafter, if the push buttons are pressed at the GPRmonitor handheld unit acknowledging the first alarm a first alarmacknowledgement signal is transmitted to the GPR monitor sensor. If afirst alarm disable signal is received, the first alarm and the thirdalarm are disabled.

If the GPR monitor handheld receives a second alarm enable signal, thesecond alarm of the GPR monitor handheld unit is enabled, as well as thethird alarm. Thereafter, if the push buttons are pressed at the GPRmonitor handheld unit acknowledging the second alarm a second alarmacknowledgement signal is transmitted to the GPR monitor sensor. If asecond alarm disable signal is received, the second alarm and the thirdalarm are disabled.

FIG. 9

FIG. 9 depicts a flowchart of the events of a preferred operation of aGPR monitor vehicle unit (e.g. the embodiment show in FIG. 4). As shownin FIG. 9, the GPR monitor vehicle unit preferably receives thecalculated true RMS voltage from the GPR monitor sensor (e.g. theembodiment show in FIG. 2) and displays the received calculated true RMSvoltage at the GPR monitor vehicle unit.

If the GPR monitor vehicle unit receives a first alarm enable signal,the first alarm of the GPR monitor vehicle unit is enabled. Thereafter,if the push buttons are pressed at the GPR monitor vehicle unitacknowledging the first alarm a first alarm acknowledgement signal istransmitted to the GPR monitor sensor. If a first alarm disable signalis received, the first alarm is disabled.

If the GPR monitor vehicle unit receives a second alarm enable signal,the second alarm of the GPR monitor vehicle unit is enabled. Thereafter,if the push buttons are pressed at the GPR monitor vehicle unitacknowledging the second alarm a second alarm acknowledgement signal istransmitted to the GPR monitor sensor. If a second alarm disable signalis received, the second alarm is disabled.

FIG. 10

FIG. 10 depicts one embodiment of a Ground Potential Rise (GPR) MonitorSystem using a transient event energy detector. FIG. 10 includes thefirst electrode 1, the second electrode 3, the voltage attenuator 5, thefirst control system 9, the first alarm 11, the firsttransmitter/receiver 13, the button 20, the second control system 19,the second transmitter/receiver 17, one or more wires 31, as describedabove. Instead of the true RMS detector 7, the embodiment shown in FIG.10 includes a transient event energy detector 51. In this embodiment,the transient event energy detector 51 produces a signal to the firstcontrol system 9 indicative of the whether or not a transient event withenergy greater than a first predetermined transient event energythreshold.

The first transmitter/receiver 13 is electromagnetically connected tothe second transmitter/receiver 17. The second control system 19 isconnected to the second transmitter/receiver 17 and the button 20 by oneor more wires 31. It is preferred to include the firsttransmitter/receiver 13 and second transmitter/receiver 17, secondcontrol system 19, and button 20, as the remote location 22 provides asa safe place for workers to acknowledge the alarm. In the alternative,the first transmitter/receiver 13 and second transmitter/receiver 17,second control system 19, and button 20 may be omitted, preferablyrelying on other safety measures (e.g. electrically insulated boots,gloves, etc.).

Upon the detection of a transient event with energy greater than thefirst predetermined transient event energy threshold, the first controlsystem 9 will enable the first alarm 11. In one embodiment, the firstalarm 11 is only for notification of a transient event with energygreater than the first predetermined transient event energy threshold.In an alternate embodiment, the first alarm 11 is a generic alarm orserves other purposes other than notification of a transient event withenergy greater than the first predetermined transient event energythreshold.

When the transient event with energy greater than the firstpredetermined transient event energy threshold, the first alarm 11 isenabled by the first control system 9 until a first alarm acknowledgmentsignal is transmitted by the second transmitter/receiver 17 and receivedby the first transmitter/receiver 13.

Preferably, the signal corresponding to the transient event energy istransmitted by the first transmitter/receiver 13 and received by thesecond transmitter and receiver 17, more preferably using a protocolsuch as defined in IEEE 802.15.4. In a preferred embodiment, the firsttransmitter/receiver 13 and the second transmitter/receiver 17 are bothan Xbee® transmitter. Preferably, the transient event energy is thendisplayed to a user at the remote location 22.

Transient Detector 51

The transient detector 51 detects transient events across the firstelectrode 1 and the second electrode 3 having energy greater than thefirst predetermined transient event energy threshold. Preferably,transient events include, but are not limited to, transient eventscaused by energizing shunt reactors and shut capacitors. The detectionand notification of these transient events will preferably put workerson notice of the dangerous conditions. Preferably, once notified,workers in the area will request that operations suspend all activitiesin the area that may result in possibly dangerous transients.

Preferably, the transient detector 51 detects a high-speed energy and alow-speed energy across the first electrode 1 and the second electrode 3(preferably, after attenuation by the voltage attenuator 5). If thehigh-speed energy minus the low-speed energy matches or exceeds thepredetermined transient threshold, the transient detector 51 sends asignal to the first control system 9 indicative of the detection of atransient.

The high-speed energy is preferably the voltage sampled at a samplingfrequency that is high enough to detect the presence of transients.Preferably, the high-speed energy is sampled at a frequency greater than1,000 Hz, more preferably greater that 2,000 Hz.

The low-speed energy is preferably the steady-state or average voltageacross the first electrode 1 and the second electrode 3. In oneembodiment, the low-speed energy is derived from the true RMS voltage.In a preferred embodiment, the low-speed energy is the voltage acrossthe first electrode 1 and the second electrode 3 sampled at low-speedsampling rate. Preferably, the low-speed sampling frequency is less than10 Hz, more preferably 6 Hz. In yet an alternate embodiment, thelow-speed energy is the derived by passing a plurality of samplesthrough one or more filters (preferably a low-pass filter). In oneembodiment, the high-speed energy is sampled at a frequency greater than1,000 Hz, more preferably greater that 2,000 Hz and the low-speed energyis derived from the high-speed samples passed through a low-pass filter.

The low-speed energy is computed by integrating the voltage detectedsquared divided by Rb, where Rb is the estimated human body resistance(preferably 1,000 Ohms). Likewise, the high-speed energy is computed byintegrating the voltage detected squared divided by Rb, where Rb is theestimated human body resistance (preferably 1,000 Ohms).

In a preferred embodiment, the high-speed energy is calculated bysampling the voltage across the first electrode 1 and the secondelectrode 3 a frequency greater than 1,000 Hz, more preferably greaterthat 2,000 Hz. Preferably, a time window is selected, preferably about ¼of a second. The following equation Eq. 1, or a related equation, isthen used to calculate the high-speed energy

$\begin{matrix}{{{Energy}(J)} = {\frac{1}{Rb}{\sum\limits_{1}^{n}{{V(t)}^{2}{\mathbb{d}t}}}}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$where Rb is the estimated human body resistance (e.g. 1,000 Ohms); n isthe total number of samples measured in the time window (e.g. 500samples for a ¼ second time window sampled at 2,000 Hz); V(T) is themeasured voltage across the first electrode 1 and the second electrode3; and dt (e.g. 0.5 ms if sampled at 2000 Hz) is the sample period,preferably and J is the energy in Joules.

Preferably, the low-speed energy is also calculated using Eq. 1, butusing a much slower sampling rate, preferably less than 10 Hz, morepreferably 6 Hz. In an alternate embodiment, the low-speed energy isestimated using the true RMS voltage, preferably using Eq. 2

$\begin{matrix}{{{Low} - {{Speed}\mspace{14mu}{{Energy}(J)}}} = {\frac{1}{Rb}V_{R\; M\; S}^{2} \times t}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$where V_(RMS) is the true RMS voltage and t is the time window used inthe high-speed calculation, preferably about ¼ of a second.

Finally, the transient event energy is computed by subtracting thelow-speed energy from the high-speed energy. Preferably, the firstcontrol system 9 signals an alarm if the transient event energy exceeds13 Joules.

In an alternate embodiment, a value relating to the energy of thelow-speed energy and the high-speed energy may be used to calculate avalue relating to the energy of the transient and the transientthreshold is properly set for the calculated value. For example, in oneembodiment, the Rb constant may be omitted resulting in an energycomputation related to the energy, but Rb times greater than the energyin Joules. In this embodiment, the transient threshold would be Rb timesgreater than the desired maximum Joule value.

FIG. 11

FIG. 11 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor using a true RMS voltage and a transient detector. FIG. 11includes the first electrode 1, the second electrode 3, the voltageattenuator 5, the transient detector 51, the first control system 9, thefirst alarm 11, the first transmitter/receiver 13, the button 20, thesecond control system 19, the second transmitter/receiver 17, one ormore wires 31, as described above. It is preferred to include the firsttransmitter/receiver 13 and second transmitter/receiver 17, secondcontrol system 19, and button 20, as the remote location 22 provides asa safe place for workers to acknowledge the alarm. In the alternative,the first transmitter/receiver 13 and second transmitter/receiver 17,second control system 19, and button 20 may be omitted, preferablyrelying on other safety measures (e.g. electrically insulated boots,gloves, etc.).

FIG. 13, also includes the True RMS Detector 7, as described above,connected to the voltage attenuator 5 and the first control system 9. Inthis embodiment, the true RMS detector 7 and the transient detector 51are both connected to the output 29 of the voltage attenuator 5.Preferably, the input of the true RMS detector 7 and the transientdetector 51 are designed to avoid interfering with the output signal ofthe voltage attenuator 5. In a preferred embodiment, the true RMSdetector 7 and the transient detector 51 both have a high-impedanceinput, or use a buffered operational amplifier to avoid attenuating theoutput signal of the voltage attenuator 5.

In one embodiment, the output of the true RMS detector 7 and thetransient detector 51 are connected to the first control system 9 via asingle input, preferably a bus or digital input, whereby the true RMSdetector 7 and the transient detector 51 are both connected to a singleinput of the first control system 9. In an alternate embodiment, theoutput of the true RMS detector 7 and the transient detector 51 are eachseparately connected to different inputs of the first control system 9.

In a preferred embodiment, the true RMS detector 7 and the transientdetector 51 are connected to the first control system 9 whereby thefirst control system 9 is capable of distinguishing a RMS voltageexceeding the first predetermined voltage detected by the true RMSdetector 7 or a transient event energy exceeding the first predeterminedtransient event energy threshold detected by the transient detector 51.In this embodiment, the first alarm 11, is capable of sendingdistinctive alarms or additional alarms are added to provide distinctivealarms. For example, the first alarm 11 may enable a pulsating alarm inthe event of the detection of a dangerous transient, and may enable acontinuous alarm in the event of a dangerous RMS voltage detected.

FIG. 12

FIG. 12 depicts a preferred embodiment of a Ground Potential Rise (GPR)Monitor whereby the first control system provides the true RMS voltageand transient event energy detection. In this embodiment, the firstcontrol system 9 provides the functionality of the true RMS detector 7,the transient event energy detector 51, or a combination thereof asdescribed above. It is preferred to include the firsttransmitter/receiver 13 and second transmitter/receiver 17, secondcontrol system 19, and button 20, as the remote location 22 provides asa safe place for workers to acknowledge the alarm. In the alternative,the first transmitter/receiver 13 and second transmitter/receiver 17,second control system 19, and button 20 may be omitted, preferablyrelying on other safety measures (e.g. electrically insulated boots,gloves, etc.).

The Predetermined Thresholds

In one embodiment, the user directly inputs the values for the firstpredetermined voltage threshold, the second predetermined voltagethreshold, the first predetermined transient event energy threshold or acombination thereof. In the alternative, the values for the firstpredetermined voltage threshold, the second predetermined voltagethreshold, the first predetermined transient event energy threshold, ora combination thereof may be calculated from factors such as userexposure time and body resistance.

In one embodiment, the user is asked to input the resistance of thereference probe and a control system computes the soil resistivity basedon the assumption of the reference probe diameter, preferably ⅝ inch,and it is driven into the soil at a depth, preferably 9 inches. Usingthe computed soil resistivity, a control system then computes the firstpredetermined voltage threshold, the second predetermined voltagethreshold, or a combination thereof.

A more convenient option is for the soil resistivity to be determined bythe sensor unit directly, for example by the Wenner Arrangement,utilizing four equally-spaced electrodes, the Three-Point Driven RodMethod, utilizing a driven ground rod and two smaller electrodes, or theTwo-Point Driven Rod Method, utilizing two identical electrodes driventhe same depth into the ground.

In yet another embodiment, the soil characteristics, more particularly,the soil resistivity is determined indirectly by connecting anelectrical resistor across the first electrode and the second electrode.The electrical resistor is used to calculate the electrical currentusing its known resistance and determining the voltage across theresistor by applying ohms law. Preferably, the determined electricalcurrent is used by a control system to enable an alarm when the currentexceeds a predetermined current threshold. When an electrical currentexceeds a predetermined electrical current threshold, a crowbar circuitis preferably used to electrically connect the first electrode and thesecond electrode without passing electrical through the ground potentialrise monitor. Preferably, the crowbar circuit has a minimized electricalresistance. Preferably, when the calculated electrical current throughthe ground potential rise monitor exceeds a predetermined currentlimited, the crowbar circuit is enabled to handle the higher electricalcurrent. Preferably, the crowbar circuit is designed to handle up to 20amps of steady-state current. Preferably, the crowbar is periodicallytemporally disabled for a short time period in order to allow the groundpotential monitor to take measurements, without damaging the groundpotential rise monitor. Preferably, the crowbar circuit has a fuse and ameans for detecting when the fuse is blown, for example optics,electrical conductivity testing, current detection etc.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the presentinvention. Numerous modifications and alternative arrangements may bedevised by those skilled in the art without departing from the spiritand scope of an electromagnetic wrap and the appended claims areintended to cover such modifications and arrangements.

All publications and patent documents cited in this application areincorporated by reference in their entirety for all purposes to the sameextent as if each individual publication or patent document were soindividually denoted.

Any element in a claim that does not explicitly state “means for”performing a specified function, or “step for” performing a specificfunction, is not to be interpreted as a “means” or “step” clause asspecified in 35 U.S.C. §112, ¶ 6. In particular, the use of “step of” inthe claims herein is not intended to invoke the provisions of 35 U.S.C.§112, ¶ 6.

1. A device for the detection of ground potential rise comprising: a. afirst electrode and a second electrode; b. a voltage attenuatorcomprising a first input, a second input, and an output; c. said firstinput of said voltage attenuator electrically connected to said firstelectrode; d. said second input of said voltage attenuator electricallyconnected to said second electrode; e. a means for determining thepresence of a dangerous ground potential connected to said voltageattenuator; f. a means for enabling one or more alarms upon thedetection of said dangerous ground potential; and g. said means fordetermining the presence of a dangerous ground potential and said meansfor enabling one or more alarms comprising one or more computers,microcontrollers, or application specific integrated circuits (ASIC); h.said means for determining the presence of a dangerous ground potentialcomprising: i. a means for determining the true RMS voltage at saidoutput of said voltage attenuator; and i. said a means for enabling oneor more alarms comprising: i. a means for enabling one or more alarmswhen said true RMS voltage exceeds a first predetermined voltagethreshold; j. a first control system comprising said means fordetermining the true RMS voltage and said means for enabling one or morealarms; k. said first control system comprising one or more storagemedias and an analog-to-digital converter; l. said analog-to-digitalconverter electrically connected to said output of said voltageattenuator; m. said one or more storage medias comprising computer codefor performing one or more calculations to determine an RMS value basedon the voltage at said output of said voltage attenuator; n. said firstcontrol system comprising a first predetermined voltage relating to saidfirst predetermined voltage threshold; and o. said first control systemcomprising a storage media comprising computer code for comparing saiddetermined RMS value and said first predetermined value.
 2. A device forthe detection of ground potential rise comprising: a. a first electrodeand a second electrode; b. a voltage attenuator comprising a firstinput, a second input, and an output; c. said first input of saidvoltage attenuator electrically connected to said first electrode; d.said second input of said voltage attenuator electrically connected tosaid second electrode; e. a means for determining the presence of adangerous ground potential connected to said voltage attenuator; f. ameans for enabling one or more alarms upon the detection of saiddangerous ground potential; and g. said means for determining thepresence of a dangerous ground potential and said means for enabling oneor more alarms comprising one or more computers, microcontrollers, orapplication specific integrated circuits (ASIC); h. said means fordetermining the presence of a dangerous ground potential comprising: i.a transient detector connected to said output of said voltageattenuator; ii. said transient detector having a means for sampling thevoltage at the output of said voltage attenuator at a low-speed and at ahigh-speed; iii. said high-speed greater than said low-speed; iv. saidhigh-speed equal to or greater than 1,000 Hz; and i. said a means forenabling one or more alarms comprising: i. a means for enabling one ormore alarms when the transient energy detected by said transientdetector exceeds a first predetermined transient energy threshold. 3.The device for the detection of ground potential rise of claim 2 furthercomprising: i. said high-speed equal to or greater than 2,000 Hz.
 4. Thedevice for the detection of ground potential rise of claim 2 furthercomprising: i. said low-speed equal to or less than 10 Hz.
 5. The devicefor the detection of ground potential rise of claim 2 furthercomprising: i. said first predetermined transient threshold is greaterthan 13 Joules.
 6. A device for the detection of ground potential risecomprising: a. a first electrode and a second electrode; b. a voltageattenuator comprising a first input, a second input, and an output; c.said first input of said voltage attenuator electrically connected tosaid first electrode; d. said second input of said voltage attenuatorelectrically connected to said second electrode; e. a means fordetermining the presence of a dangerous ground potential connected tosaid voltage attenuator; f. a means for enabling one or more alarms uponthe detection of said dangerous ground potential; and g. said means fordetermining the presence of a dangerous ground potential and said meansfor enabling one or more alarms comprising one or more computers,microcontrollers, or application specific integrated circuits (ASIC); h.said means for determining the presence of a dangerous ground potentialcomprising: i. a means for determining the true RMS voltage at saidoutput of said voltage attenuator; and i. said a means for enabling oneor more alarms comprising: i. a means for enabling one or more alarmswhen said true RMS voltage exceeds a first predetermined voltagethreshold; j. said means for determining the presence of a dangerousground potential comprising: i. a transient detector connected to saidoutput of said voltage attenuator; ii. said transient detector having ameans for sampling the voltage at the output of said voltage attenuatorat a low-speed and at a high-speed; iii. said high-speed greater thansaid low-speed; iv. said high-speed equal to or greater than 1,000 Hz;and k. said a means for enabling one or more alarms comprising: i. ameans for enabling one or more alarms when the transient energy detectedby said transient detector exceeds a first predetermined transientenergy threshold.
 7. The device for the detection of ground potentialrise of claim 6 further comprising: a. a first transmitter/receiverconnected to said means for enabling one or more alarms; b. a secondtransmitter/receiver electromagnetically connected to said firsttransmitter/receiver; and c. a button connected to said secondtransmitter/receiver.
 8. The device for the detection of groundpotential rise of claim 7 further comprising: a. a first displayconnected to said first control system; b. said first display displayingsaid determined true RMS voltage; c. a second control system connectedto said second transmitter/receiver; d. a second display connected tosaid second control system; and e. said second display displaying saiddetermined true RMS voltage.
 9. The device for the detection of groundpotential rise of claim 8 further comprising: a. said high-speed equalto or greater than 2,000 Hz; b. said low-speed equal to or less than 10Hz; and c. said first predetermined transient threshold is greater than13 Joules.
 10. The device for the detection of ground potential rise ofclaim 9 further comprising: a. a first control system comprising saidmeans for determining the true RMS voltage and said means for enablingone or more alarms; b. said first control system comprising one or morestorage medias and an analog-to-digital converter; c. saidanalog-to-digital converter electrically connected to said output ofsaid voltage attenuator; d. said one or more storage medias comprisingcomputer code for performing one or more calculations to determine anRMS value based on the voltage at said output of said voltageattenuator; e. said first control system comprising a firstpredetermined voltage relating to said first predetermined voltagethreshold; and f. said first control system comprising a storage mediacomprising computer code for comparing said determined RMS value andsaid first predetermined value.
 11. The device for the detection ofground potential rise of claim 9 further comprising: a. said means fordetermining the true RMS voltage comprising a true RMS voltage detectorelectrically connected to said output of said voltage attenuator andsaid means for enabling one or more alarms.